Sample size = n = 1100 Sample number of events = x = 860 Sample proportion = p = x/n = (860/1100) = 0.7818 (point estimate of population proportion) (1-0) Stanadard Error = = sqrt(0.7818*(1-0.7818)/1100) = 0.0125 n Confidence Level = 95 Significance Level = a = (100-95)% = 0.05 Critical value = z* = 1.96 [Using Excel =ABS(NORMINV(0.05/2,0,1))] Margin of Error = z* (standard error )= 1.96*0.0125 = 0.0244 Lower Limit =P – Margin of Error = 0.7818 -0.0244 = 0.757 Upper Limit =p + Margin of Error = 0.7818 +0.0244 = 0.806